Kalmar War

The Kalmar War occurred from 1611 to 1613 when Sweden and Denmark-Norway warred for hegemony over the Baltics. The war was the last time that Denmark was able to successfully defend its control over the Baltic Sea.

Background
In the early 17th century, the rulers of Denmark-Norway sought to pursue dynastic expansion aspirations into northern Germany and to protect the country and its hegemony over the Baltics from Sweden. From 1563 to 1570, Sweden and Denmark fought in the Northern Seven Years' War. In 1607, King Charles IX of Sweden, seeking to avoid paying Denmark's "Sound Dues", began collecting taxes on Danish territory in Norway, planning to create a new trade route through sparsely-populated Lappland. Denmark protested against Sweden's evasion of their taxes, and, in 1611, they declared war in order to regain control of Lappland.

War
The Danes attacked from Kristianopel towards Kalmar, from Halmstad towards Jonkoping, and from Norway towards Alvsborg, and, while a 6,000-strong Danish army took Kalmar, the Swedes stormed Kristianopel and blunted the Danish assault. In the summer of 1611, the Swedes invaded Norwegian Jamtland and Harjedalen, both of which fell without much resistance. However, the locals eventually rose up against the Swedes and expelled them in the fall of 1612. In 1612, the new Swedish king Gustavus Adolphus was defeated by the Danes in the Battle of Vittsjo and nearly drowned during the surprise attack, and the Danes also took Alvsborg and Gullberg in Gothenburg. The Danish attempts to assault Stockholm, however, failed due to the Swedes' scorched earth policies, and the Danes were soon unable to pay their mercenaries. On 20 January 1613, pressured by King James I of England, the two sides made peace, and, while the Swedes had to pay a large indemnity and forfeit their conquered lands, they were exempted from the Sound toll.